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We have been thru alot of field R&D over the last 3 yrs. and are still making changes to these systems some hardware but mostly programming and setting's and now we have building automation driving a couple of these.I know some of these company's don't want us talking about this too much over an open forum because of all these issue's it is hard enough getting answer's out of them as it is.chiller rob is right we will need to keep this line of communication open because these machine's are not going away you will see alot more of them in the near future.

i think if we talk about the retrofit appications and the fundamentals of compresssor control we should be ok...

if you are looking at an open drive replacement with DX evap these are some things that we have found helpful...

1. suction and discharge headers
2. install different discharge checks
3. roll liquid line for motor cooling off bottom
4. if using dx evaps... install exvs with independant sh
5. try incorporate stable head pressure control in the job
6. use kiltech for multiple compressor circuit IMO
7. control llsols off comp i/o run contacts...
8. for multiple exv's use stand alone drivers
9. try to use min load valve in all applicaitons
10.try to stay water cooled and keep the CR low
11.try to uses a reciever when ever possible
12.keep some oil in the circuit to lubriate the EXV's

if you are looking at a flooded/ flooded converstion...

1. vfd on condenser water pump
2. keep you head pressure high
3. try to go with 134a application
4. if using exv set super heat setting at -2.0 df

with all applications be aware of the compressor map and really get into what is going on at startup... if you need to move into the map so the compressor will load up this is accomplished by tuning the exvs and/or head pressure...

if this is not accomplished the compressor will come on line and just idle... then once the compressor comes into the map it will race to setpoint and cause some problems...

this is most common when running the compressor on chiller mode program built into the compressor but also can be seen with modbus or analouge input control...

keep in mind if the compressor experiences low suction it will speed up to stay on line and may futher compound what ever problem you have feeding refrigerant to the low side...

if your are just getting into the game stay with comfort cooling applications... maintaining a stable supply temp in a process application can get tricky especially with multiple compressor circuit applications...